When I have a DAW that's hosting VSTi's or am using a standalone VSTi (like SampleTank) and outputting MIDI to them from Noatikl via a loopback driver, Noatikl refuses to play. I click on the 'play' button, and nothing happens. When I close the DAW or standalone VSTi, Noatikl plays just fine.

Thanks for reaching out. Just checking... although this is couched in terms for Reaper, in Noatikl do you have "Sync?" set to on, and in your DAW are you pressing the play button? Are you running on Mac or Windows, and which version and what loopback driver are you using?